Week 2- Reciprocal Altruism

Question 1

What forms can altruism take

Answer 1

Alarm calls, group hunting.

Question 2

Evolutionary stable strategies(ESS)

Answer 2

An ESS describes a trait which cannot be ‘invaded’ by alternative strategies

Question 3

Example of pure altruism

Answer 3

Through the idea of a single gene for pure altruism, a population with this gene would have better survival than populations without, through equitable distribution of food

Question 4

Downside of pure altruism

Answer 4

The pure altruists are vulnerable to invasion by other species that do not carry the gene. Therefore, the defectors take advantage of the altruist and the altruists eventually die out as they are left at a disadvantage as they are not receiving any benefits

Question 5

Conclusion of the example

Answer 5

Benefit to the group, by itself, is unlikely to be a powerful selection force.
In this case of altruism, paying a cost to benefit the group can make the group more successful, but individuals who don’t pay the cost will be even more successful

Question 6

Two key ideas of how altruism can be evolutionary stable

Answer 6

1) kinship and genetic relatedness
2) Reciprocal altruism

Question 7

Kinship and genetic relatedness

Answer 7

Kin selection- we can expect many or even most species to demonstrate altruism towards their relatives

However,
There are many situations where humans voluntarily and knowingly help friends and non- relatives at a cost to themselves

Question 8

Reciprocal altruism

Answer 8

Trivers identified another mechanism for evolved altruism, in which aid is given to others with the prospect of future payback
- reciprocal altruism means that self-sacrifice can actually be beneficial, if the aid will be returned when needed

Question 9

What are the important conditions trivets identified for reciprocal altruism

Answer 9

• it requires a species with the cognitive abilities to identify and remember other individuals, their actions, the outcomes of those actions, and even their motives.
• these abilities are necessary to identify chests and repaying debts
  This suggests a long- lived species living in close-proximity with other members

Question 10

Prisoners dilemma

Answer 10

In a prisoners dilemma, no matter what your accomplice does, you are better off if you defect rather than co-operate